Average power of A.C.

We know that the average power of A.C. is IVcosθ, where I and V are RMS and θ is the phase difference. I would like to ask in common application, such as power of a lamp, computer, fan etc. Can we simply assume the phase difference is zero and get a fairly accurate answer? Thank you.

I'm sure others with more knowledge in this area will post a better response. Power Factor for switching power supplies that qualify for UL or other certs control the PF so essentially (0 - EDIT, this should be 1) for that one. Incandescent light bulbs are for the most part (0 - EDIT this should be 1) as well. Fans or other motor appliances are probably not. There are/were devices that are sold to view the power factor (watt wizzard I think was one) and other devices that are suppose to compensate to yield lower usage for those devices.

So to answer your question, no I don't think you can assume a power factor of (0 - EDIT this should be 1) because one location may have many fans, or other devices that might cause a 5 - 10% difference. However, if your location is just electronics and lights you might be able to assume PF of (0 - EDIT this should be 1).